Trigger mechanism



May 8, 1945. P, PALE 2,375,381

TRIGGER MECHANISM Filed Sept. 16, 1943 2 Sheets-Sheet 1 gram fay] falema ,8, 1945. PALE 2,375,381

TRIGGER MECHANISM Filed Sept. 16, 1943 2 Sheets-Sheet 2 Paul PalePatented May 8, 1945 UNHTED STATES PATENT OFFICE TRIGGER MECHANISM PaulPal, Wilkes-Barre, Pa. 1

Application September 16, 1943, Serial No. 502,658

14 Claims.

This invention relates to trigger mechanism for firearms, and moreparticularly to such mechanism wherein a long trigger stroke is utilizedand the point within the limits of the stroke at which the firingmechanism is tripped varies indeterminately and infinitely.

Modern firearms are designed to provide infinitesimal movement of thetrigger from cocked to tripped position. Novicesare taught by expertmarksmen that the trigger must not be pulled but squeezed verygradually. In other words, the firing is not accomplished by moving thetrigger through an appreciable arc, but rather by a gradual increase ofpressure against the trigger until it suddenly trips and is -free. Toincrease the safety factor, rules. have been established for themajority of competitive meets which bar the use of any fire armrequiring less' than a certain specified minimum trigger pressure tofire. This trigger action, light or heavy, presents many hazards to goodmarksmanship.

First, the gradual, smooth increase in pressure upon the trigger isdifiicult to attain, and to most persons comes only through longpractice. Uneven or jerky increase in pressure will cause the gun to bedeflected from the target and thus spoil the shot. Second, at theinstant of release, the trigger mechanism is relieved of its load andthe trigger moves freely. The pressure put upon the trigger to fire thegun causes the trigger to snap back quickly to its limit of movement. Onthose rare occasions, with mode rn ammunition, when a shell hangs firefor a brief interval; the sudden movement of the trigge r after releasewill cause the gun to deflect and be off the target when the shell firesbelatedly. Third, and most important, expert and experienced marksmenlearn the action of their firearms after but a few shots so that theysubconsciously know or sense the instant that the trigger is ready torelease. Only a comparative few are so constituted that they can preventa slight involuntary flinch in anticipation of the explosion to follow.This also spoils the aim. Even though the marksmanbecomes proficient inthe operation of the trigger, he must learn to control his ownreactions. He must keep his nerves'under such rigid control that thehuman tendency to fiinch in anticipation of the noise or shock will beovercome.

The object of this invention is to provide trigger mechanism which willovercome these mental as Well as mechanical handicaps to goodmarksmanship by incorporating means to give a long equalized triggerpull before and after release, and an indeterminate point of fire thatvaries infinitely within limits less than the full, trigger stroke andis impossible to predetermine,

attachment for stock firearms, the mechanism including an auxiliarytrigger and accompany-g ing mechanism to be secured to the firearm toactuate the existing trigger, or may bebuilt into the gun as a partthereof and have a single trigger. I I

A further object of the invention is to provide in such a device meanswhereby the auxiliary trigger may be moved throughout its full rangewhen the safety is on or the gun is jammed without damage to thefirearms mechanism or that of the attachment. It is also contemplatedthat in the event of failure of a portion of the mechanism in theattachment, an emergency firing of the gun may be accomplished by actualcontact of the auxiliary trigger with the existing trigger if thetrigger pull is continued.

The inventive concept includes means adapted v to be applicable to anytype trigger actuated firearm regardless of the trigger movement of thefirearm as it is being cocked.

Broadly, the object of the present invention is to negative theprobability of muzzle deflection during firing of the firearm byproviding means to ensure smooth trigger operation and provide for aninfinite number of points of fire so that the explosion will come as asurprise to avoid anticipation.

It is an object of the invention to provide means whereby an instructormay control the firing of the gun while standing far enough away topermit full freedom of movement and vision to the pupil.

Other objects of the invention will become apparent from the followingspecification taken in conjunction with the drawings which accompanyandform a part of the specification and throughout the several figures ofwhich the same characters of reference are used to denote identicalparts throughout.

In the drawings:

Figure 1 is a side elevational view of an automatic pistol showing theinvention in the form of an attachment;

Figure 2 is an enlarged side elevation of a portion of a gun with thecover plate of the attachment removed;

Figure 3 is a view similar to Figure 2 showing parts in their positionafter the gun has fired and the trigger is on its return stroke;

Figure 4 is a vertical section taken on the line 4--4 of Figure 2;

Figure 5 is a horizontal section .taken on the line 5-5 of Figure 2;

Figure 6 is a perspective view of the trigger actuating unit;

Figure 7 is a detail view of a modified form of fulcrum cam actuatingmeans;

Figure 8 is a view similar to Figure 2 showing the mechanism as adaptedfor use with a gun having a diiferent trigger movement;

Figure 9 is a perspective view of a gun showing remote control means forfiring the gun;

Figure 10 is a fragmentary section through the case showing themodification necessary for the use of remote control;

Figure 11 is a fragmentary section taken through the remote controlmeans at right angles to the showing in Figure 10.

Referring to the drawings in detail and first adverting to that form ofthe invention shown in Figures 1 to 6, the invention is shown as appliedto an automatic pistol I. It is to be understood that the automaticpistol is merely illustrative of automatic guns in general, or any 1firearm having an equivalent trigger movement.

In Figures 1 to 6, the invention is in the form of an attachment 2 to besecured to the side of the gun by any appropriate means and in the mostdesirable position, on the gun illustrated, above and adjacentthe'trigger guard. It comprises a small case 3 having a base plate 4 andside walls 5. A cover plate 6 completes the case and protects themechanism which the case houses.

Near the lower right hand corner of the case,

as viewed in Figure 2, a stud 1 projects outwardly from the base plateto form a pivot for a trigger actuating plate 8. Preferably, althoughnot necessarily, stud I is in axial alignment with the pivot for thetrigger 9 of the gun. The trigger actuating plate 8 has a body portionIn generally triangular in shape, and a depending trigger engaging arm Iextending downwardly from the body portion adjacent the pivot l. Thetrigger engaging arm passes through an opening 4| in the wall of thecase and is offset laterally as at |2 below the body of the gun andwithin the circle of the trigger guard to permit the arm to lie fiatalong the side of the trigger. A lip |3 at the lower extremity of thearm H is bent at right angles to the plane of the arm H to overlie thefront of, and to apply pressure to, the trigger 9 at the tip. Theforward portion of the base has a tongue struck out and split All toform an upstanding ear l4 and a rearwardly extending lug l5 passing overthe edge of the trigger actuating plate to prevent the plate from movingout of its normal plane of movement.

A second plate I1 is pivoted to the trigger actuating plate 8 by meansof pin I8. A- portion of plate ,l'! is bent upward and over the plate,as at |9, and a shaft 20 extends from the arm I9 to the plate I! andcarries an irregular shaped fulcrum cam 2|. The irregularities of thecam have been greatly exaggerated in the drawings to graphicallyillustrate the principle of the invention, but, as a matter of fact, thecam will be much more nearly round and the depressions very slight.

Trigger actuating plate 8 has an opening 22 through which a stud 23passes. Stud 23 is carried by the case base plate and forms a pivot foran auxiliary trigger 24. The lower end of trigger 24 passes through theopening 4| and is offset laterallly, as at 25, to position the fingerpiece 26 in substantially the same plane as the trigger 9. Trigger 24has an arcuate portion 21 to fit around the fulcrum cam and a bearingpoint 28 to engage the cam when the trigger is actuated.

Upstanding lugs 29 and 30 on the trigger actuating plate 8 and secondplate ll, respectively, form terminals to which are connected theopposite ends of the spring 3|. Under ordinary circumstances, plates 8and H act together as a single unit, the spring 3| being of suflicientstrength to hold the plate I! against the stop 32 projecting upwardlyfrom the plate 8.

Pivoted to the base plate of the case at 33 is a latch member 34provided with a sloping shoulder 35 to cooperate with a shoulder 36provided at the edge of lug 28, as will be hereinafter described. Latch34 is biased by a spring 31 for movement in a clockwise direction. Thelatch is also provided with a cam face 38 cooperating with a nose 39 onthe trigger 24 for returning the latch to its normal inoperativeposition.

A spring 40 connects the upstanding ear M to the trigger 24 to hold thetrigger in its forward position. The spring is attached to the trigger24 at such a position that the spring must be deflected from itsstraight line position in order to pass around and frictionally engagethe fulcrum cam 2|.

When the auxiliary trigger is actuated, it swings around its pivot 23and the point 28 presses against the fulcrum cam 2| and forces the camand the attached plate I! downward. The spring 3| is of suflicientstrength to maintain plates I7 and 8 in their relative positions so thatthey operate as a unitary member, and when plate I! is forced downwardplate 8 moves down around its pivot 1, causing the trigger 9 to move andso fire the gun. Trigger actuated plate 8 must move to a certain pointin order to cause the trigger 9 to release. Stop screw II is adjusted tostop the movement of the plate when this point is reached. During itsrearward movement, auxiliary trigger 24 has its bearing point 28 incontact with the fulcrum cam 2| and there is a rotating motion of thebearing point 28 upon the cam 2| as the plates move downward. As cam 2|has an irregular outline, the length of the stroke of the auxiliarytrigger will vary depending upon the surface of the cam 2| contacted bybearing point 28. Spring 4|! draws the auxiliary trigger forward untilit strikes the end of opening 4|. Therefore the auxiliary trigger alwaysstarts its stroke from a fixed point. The plate 8 has a positive limitat the end of its downward movement. The particular portion of cam 2|which strikes the trigger will determine the upward limit of movement ofthe plate. In this manner the amount of downward movement the plate willhave will be varied. As the trigger moves the plate, its stroke isproportionately varied. If the face 28 contacts a high point in the cam.the trigger stroke will be relatively short, and if it contacts a lowpoint on the cam, the trigger stroke will be proportionately increased.It is obvious that intermediate points will vary the stroke inaccordance with their distance from the center of the cam.

amass-1w As the trigger is drawn backward; the nose 39 on-the upperportion or the-trigger will leave of the spring 3! untilits-uppersurface strikes the under side of the shoulder 36. As the-triggercontinues to move rearwardly rocking the" plate 3, the shoulder 36will'move' forward, freeing the shoulder 35 and permitting the latch torise be-r hind shoulder 36; As the shoulder 35 slopesj the rise isgradual and the latch becomes fu11y'en-" gaged just about the time theplate 8 has reached its limit of movement. The shoulder 35will hold theplate in its downward position, preventing its return, at any pointafter its initial engagement, so that if the' ma'rksman should-decidenot to fire, the cam will have a' new setting the'next time thetriggeris pulled.

The latch-mechanism is provided to hold the plate downward while theauxiliary trigger returns to its position of rest" under the influenceof the"spring 40, In this manner the auxiliary trigg'er'isspac'ed fromthe fulcrum cam 2i during its return swing and the cam is free to berotated by the frictional bearingof the convolutions of' the contractingspring 40 against its periphery. v

F-ulcrum cam 2| is rotated a little in clockwise direction during thefiring stroke'b'y contact with the auxiliary trigger, and it will beobvious that during the firing stroke the frictional bearing of the.trigger against the cam will prevent its oppo" site rotation bythespring 40. The cam will be moved by" the spring on the return strokewhen thi pressure is released by means of the latch holding the plate inits downward position. Thus thecam will rotate in a clockwise directiononly. This will not provide a positive drive to rotate the" cam and itmay be rotated more or less, depending upon the slippage between springand carh and the length of stroke of the auxiliary trigger. This is truewhether the gun is actually fired or not.- This enhances the value ofthe device, as it renders the firing point even more indeterminate thanwould be the case if the cam were positively rotated through a setdegree of arc each time'the gun was fired. By this arrangement aninfinite movement of settings is provided between the highest and lowestpoints of the cam. I

Just before the auxiliary trigger 24 reaches the limit of its forwardswing, the nose 39 contacts cam face 38 of the latch and rotates thelatch' in a counterclockwise direction, releasing the plate 3andpermitting it to return to its position of rest, which position isdetermined by the cam 2| striking the trigger bearing point 28. Spring40' serves the mp1 function of returning the auxiliary trigger to itsinoperative position,- rotating the cam 21, and drawing the plates 8 andIT back to their inoperative position. The two plates 8 and H, as hasbeen described, function as a single plate when all of the mechanism isin working order. If, however, the safety lock of the gun is on, the guntrigger 9 is immovable. If some means were not provided to compensatefor this, actuation of the auxiliary trigger 24 might cause breaking orstraining of mechanism. For this reason, two plates are providedpivotedas at I8 50 that should the gun be locked or mechanism jammed, plate I'lmay move downward in its usual manner. but plate 8 will remainstationary, the spring 3| lengthening to permit this movement. When theauxiliary trigger is released, the plate I! will return to its formerposition; which position" is determined by the cam 21' abutting thetrigger. spring t r has the additional'fun'ctiori of providing smoothcontinuation'of auxiliary trigger pull beyondfiring'point' when the guntrigger has released, and itsre= sistance has greatly lessened suddenly.The tension of spring 3| added to that of spring 4Bwill preserve auniform pull.

This structure provides a longitudinal stroke throughthe limits of whichthe pressure is substantially uniform'. The firing will take place at anindeterminate point in the stroke'with nothing totindicate to themarksman when thefiring is to take place and there is no sudden drop'in'the pull of the auxiliary trigger after gun has fired. The firstindication he'will have that the firing mechanism has been released willbe the recoil and sound of the explosion. Any phy-sical'reaction orfiinching which may then occur will not spoil the shot as the bullet hasby that time left the gun.

If the mechanism should break, the user of the gun may still fire it bycontinuingthe backward stroke of the auxiliary trigger until it contactsthe face of trigger 9 and by actual pressure moves the gun'trigger' 9.

A slight modification of the above structure is shown in Figure 7.wherein a cam follower t2" is pivotally connected to the auxiliarytrigger 24 as at l3 and provided with a downwardly extending arm 44 towhich the end of the spring Ml is attached. .The pull of spring willkeep the long arm 45' of the follower tight against the surface of thecam and the friction between the follower and the cam will cause the camto rotate on the return stroke of the auxiliary trigger. Such a deviceas this would be used primarily in the gun of an expert, where even thealmost imperceptible sound of the convolutionsof the spring rubbingagainst the surface of the cam might give some indication as to when thefiring point is about to be reached.

In Figure 8, the device is shown as applied to a revolver. A slightlymodified mechanism must be supplied as the trigger action of a revolveris difierent from that of an automatic. Substantially the same movementof the trigger takes place to release the firing mechanism, but thetrigger is moved forward when the gun is fired and then moves backward aconsiderable distance as the hammer isdrawn back. This is a necessarymovement involved in the rotation of the cylinder or to cook the hammer.Consequently, provision must be madein the attachment to permit thetrigger to follow its regular cycle of movement. This is accomplished byforming the plate 8 in two sections Z6 and 41, the twosections beinglocked for unitary movement when the gun is fired, by means of a latch48'; Latch 4-8 is pivotally connected to the main portion of plate 8 asat 49 and is biased towards latching position by means of a spring 50.The latch has a relatively short arm 5| extendingat the opposite side ofthe pivot from the keeper, which lever is beveled at its upper edge forcooperation with a cam 52 fixed to pivot upon the auxiliary trigger 24.Cam 52 is held outward against a stop 53 by means of spring 54. When theauxiliary trigger is moved, cam 52 will slide over cam 55 of the latch,and as the latch is in position holding the two parts of the plate 8together, the revolver trigger will be actuated and the gun fired. Asthe auxiliary trigger 24 returns to its position of rest, the cam 52,due to its frictional engagement with the cam face 55, will swing out-'ward around its pivot, thus preventing its passing the latch on itsreturn without first moving the latch about its pivot. This will releasethe trigger section ll of the plate 8 and allow the revolver trigger thefreedom of movement necessary to follow -its regular cycle as the gun iscooked.

As shown in Figures 9, 10 and 11, the present invention lends itselfideally to the use of remote firing control by instructors. The bottom 4of the case may be extended slightly, as shown at 5B, and provided witha substantially square opening 51, and the plate 8 may have a similarextension 58 and opening 59. The housing will also have to be dropped toprovide opposite openings 60 which form bearings for a remote controlrod 6!. Rod 6| may be made in sections coupled together by flexibletubing 62, and carry at its end a metal control shaft 63. The controlshaft has circular ends 64 to seat in the openings Gil in the housingwhen the rod has been inserted in place, and the rod is clamped inposition by means of a knurled nut 55. An indicating arrow 66 isattached to the opposite end of the metal control rod and serves to showthe position of the shaft in the casing. The central portion of theshaft is cut away, as at 61, leaving only a quadrant of the shaft as at68. The central portion of the shaft passes through the openings 51 and59 in the extensions 56 and 58, respectively, with the shaft bearingagainst the sides 69 and T0 of the opening 59. When the auxiliarytrigger 24 is 'moved, only the plate I! will move, as the centralportion of the control rod 63 prevents movement of the trigger actuatingplate 8. At such time as the instructor desires to fire the gun, the rodis rotated to move the portion 58 to the opposite side of the opening 59and the contraction of the spring 3| will move the plate 8 and actuatethe trigger to fire the gun.

It is to be understood that the invention is adaptable either to anattachment or as a part of the firearm. It, is only necessary that theplate 8 be in operative connection with that part of the firearmsmechanism which releases the firing mechanism. When it is to be attachedto a firearm, the firearms trigger will be the firing mechanism release,necessitating the use ofan auxiliary trigger, but when built into afirearm will be connected to only that portion of the trigger which isinside the firearm, the remainder of the trigger being eliminated.

Although certain specific, practical embodiments of the invention havebeen shown and described, it is to be understood that the inventiveconcept is capable of many adaptations and changes from the structureshown and the invention is to be limited only by the scope of theappended claims.

Having thus described my invention, what I claim is:

1. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, and pivoted means having a perimeter which varies indistance from the pivot interposed between said trigger and said memberfor transmitting movement of said trigger to said member, said meansbeing shiftable where by the length of the trigger stroke is varied onsuccessive operations of the trigger.

2. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, a pivoted cam having a perimeter which varies in distancefrom the pivot interposed between said trigger and said member fortransmitting movement of said trigger to said member, and means toimpositively rotate said cam each operation of the trigger whereby thelength of the trigger stroke is varied on successive operations of thetrigger.

3. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, a pivoted cam of irregular outline having its peripheryat varying distances from the pivot interposed between said trigger andsaid member for transmitting movement of said trigger to said member,and frictional means to impositively rotate said cam on each operationof the trigger, whereby the cam is rotated in indeterminate amounts andthe length of the trigger stroke is varied on successive operations ofthe trigger.

4. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, a pivoted cam of irregular outline having its peripheryat varying distances from the pivot interposed between said trigger andsaid member for transmitting movement of said trigger to said member,and means to bias said trigger toward inoperative position, said meansbeing in frictiona] engagement with the periphery of said cam toimpositively rotate said cam in indeterminate amounts during eachtrigger stroke whereby the length of th trigger stroke is varied onsuccessive operations of the trigger.

5. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, a pivoted cam of irregular outline having its peripheryat varying distances from the pivot interposed between said trigger andsaid member and in contact with said trigger for transmitting movementof said trigger to said member, means to bias said trigger towardinoperative position, said means being in frictional engagement with theperiphery of said cam whereby the cam will be impositively rotated inindeterminate amounts during each stroke of the trigger, and means tohold the member in operative position during the return stroke of thetrigger whereby the trigger will be removed from engagement with the camto permit the cam to rotate freely.

6. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, a second member pivoted to said firstmentioned member,yieldable means interconnecting said members to cause said members tooperate in unison, a cam carried by said second member in contact withsaid trigger for transmitting movement of said trigger to said secondmember.

'7. An attachment for firearms having a trigger comprising, a triggeractuating member adapted to contact said trigger, an auxiliary trigger,and pivoted means having its perimeter at varying distances from thepivot interposed between said auxiliary trigger and said triggeractuating member for transmitting movement of said auxiliary trigger tosaid trigger actuating member, said means being shiftable whereby thelength of stroke of the auxiliary trigger is varied on successiveoperations of the auxiliary trigger.

8. An attachment for firearms having a trigger comprising, a triggeractuating member adapted to contact said trigger, an auxiliary trigger,a pivoted cam of irregular outline having its perimeter atvaryingdistances from the pivot carried by saidtrigger actuating memberfor transmitting movement of said auxiliary trigger to said triggeractuating member, and means to impositively rotate said cam whereby thelength of stroke of the auxiliary trigger is varied on successiveoperations of the auxiliary trigger.

9. Trigger mechanism for firearms comprising, a trigger,firing'mechanism release means, an actuating member for said firingmechanism release means operable by said trigger, said actuating membercomprising relatively movable sections, means to unite the sections forunitary movement when the firearm is to be fired, and means to releasesaid uniting means after the firearm has been discharged to permitindependent movement of-the said sections.

10. Trigger mechanism forfirearms comprising, a trigger, firingmechanism release means, an actuating member for said firing mechanismrelease means, a cam interposed between said trigger and said actuatingmember to transmit movement of said trigger to said actuating member,said actuating member comprising relatively movable sections, latchmeans to unite the sections for unitary movement when the firearm is tobe fired, and means to release said latch after the firearm has beendischarged to permit independent movement of the said sections.

11. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, an actuating member for said firing mechanismrelease means, a, cam interposed between said trigger and actuatingmember to transmit movement of said trigger to said actuating member,means to rotate said cam, said actuating member comprising relativelymovable sections, latch means to unite the sections for unitary movementwhen the firearm is to be fired, and means to release said latch afterthe firearm has been discharged to permit independent movement of thesaid sections.

12. In trigger mechanism for firearms as claimed in claim 5, meanscarried by said trigger to release said member holding means as thetrigger approaches its position of rest.

13. Trigger mechanism for firearms comprising, a trigger, firingmechanism release means, a member to operate said firing mechanismrelease means, a pivoted cam of irregular outline interposed betweensaid trigger and said member for transmitting movement of said triggerto said member, means to bias said trigger toward inoperative position,a link interposed between said trigger and said biasing meansfrictionally contacting said cam and urged toward said cam by saidbiasing means for impositively rotating the cam in indeterminate amountsduring each stroke of the trigger.

14. In trigger mechanism for firearms as claimed in claim 6, remotecontrol means comprising, a rod rotatably connected to said firearm, anda cam carried by said rod to engage said first-mentioned member toprevent its movement when the cam carried by the rod is in one positionand to release the member when the rod is rotated.

PAUL PALE.

